Genetic mechanisms
used by the tobacco budworm moth and a type of roundworm to elude the
toxic effects of the most widely used biologically produced pesticide
were pinpointed by two separate research teams, according to a Reuters
article. The discovery could inspire ways to keep bugs in check without
resorting to synthetic chemicals.

Bt, Bacillus thuringiensis,
is a naturally occurring biological pesticide widely used by organic farmers
and a least-toxic alternative to chemical pesticides. It acts by inflicting
intestinal damage on crop pests. Insects and worms adapt to Bt, developing
resistance, as they do with man-made chemical pesticides and render it
ineffective.

"By actually
understanding how resistance takes place, we can develop strategies to
combat it," said Raffi Aroian, a biologist at the University of California
at San Diego who led one of the research teams. "But the first step
toward that is understanding at the molecular level how this happens."

Aroian's team studied
mutant genes discovered in the roundworm Caenorhabditis elegans that confer
resistance to a particular Bt toxin, cloned one of the five mutant genes,
and compared differences in the proteins produced by the mutant gene and
the corresponding normal gene. The comparison showed that the roundworms'
Bt toxin resistance stemmed from the loss of an enzyme that adds carbohydrates
to proteins and fats. Researchers from Clemson University in South Carolina,
North Carolina State University and the University of Melbourne in Australia
also identified a gene in the tobacco budworm moth that confers high levels
of Bt resistance in the moth.

"This is a first
step to understanding the development of Bt resistance by insect pests,"
said Clemson biologist Linda Gahan, who led the study. "This discovery
will open the door for other researchers and monitoring governmental agencies
to assess resistance mechanisms and management strategies in insect pests."

To view the full article,
see http://www.planetark.org/dailynewsstory.cfm?newsid=11902&newsdate=06-Aug-2001